diff --git a/src/Perspex.Application/Application.cs b/src/Perspex.Application/Application.cs
index ac93f82fec..f0a3c1a8ee 100644
--- a/src/Perspex.Application/Application.cs
+++ b/src/Perspex.Application/Application.cs
@@ -119,6 +119,9 @@ namespace Perspex
             private set;
         }
 
+        /// <summary>
+        /// Gets the application clipboard.
+        /// </summary>
         public IClipboard Clipboard => _clipboard.Value;
 
         /// <summary>
diff --git a/src/Perspex.Base/Metadata/XmlnsDefinitionAttribute.cs b/src/Perspex.Base/Metadata/XmlnsDefinitionAttribute.cs
index 63371bf80f..8e9fddc50b 100644
--- a/src/Perspex.Base/Metadata/XmlnsDefinitionAttribute.cs
+++ b/src/Perspex.Base/Metadata/XmlnsDefinitionAttribute.cs
@@ -1,21 +1,35 @@
-using System;
-using System.Collections.Generic;
-using System.Linq;
-using System.Text;
-using System.Threading.Tasks;
+// Copyright (c) The Perspex Project. All rights reserved.
+// Licensed under the MIT license. See licence.md file in the project root for full license information.
+
+using System;
 
 namespace Perspex.Metadata
 {
+    /// <summary>
+    /// Maps an XML namespace to a CLR namespace for use in XAML.
+    /// </summary>
     [AttributeUsage(AttributeTargets.Assembly, AllowMultiple = true)]
     public class XmlnsDefinitionAttribute : Attribute
     {
-        public string XmlNamespace { get; set; }
-        public string ClrNamespace { get; set; }
-
+        /// <summary>
+        /// Initializes a new instance of the <see cref="XmlnsDefinitionAttribute"/> class.
+        /// </summary>
+        /// <param name="xmlNamespace">The URL of the XML namespace.</param>
+        /// <param name="clrNamespace">The CLR namespace.</param>
         public XmlnsDefinitionAttribute(string xmlNamespace, string clrNamespace)
         {
             XmlNamespace = xmlNamespace;
             ClrNamespace = clrNamespace;
         }
+
+        /// <summary>
+        /// Gets or sets the URL of the XML namespace.
+        /// </summary>
+        public string XmlNamespace { get; set; }
+
+        /// <summary>
+        /// Gets or sets the CLR namespace.
+        /// </summary>
+        public string ClrNamespace { get; set; }
     }
 }